Impact of switching constraints on selection diversity performance

Selection diversity (SELDIV), in which the best of N channel outputs is selected, provides significant diversity gain for digital communications over fading channels. Classical SELDIV analysis assumes that the best channel is immediately selected, implying no constraint on the switching rate of the system. We obtain an exact result for the average BER, as a function of the time since the last switch. Our results assume BFSK modulation and Nakagami (1960) fading with an arbitrary correlation function, treating Rayleigh fading as a special case.